A stroke occurs when a portion of the brain has insufficient blood flow. There are generally two kinds of strokes, hemorrhagic and ischemic. Hemorrhagic stroke occurs when a blood vessel in the brain ruptures or leaks. This can prevent other areas of the brain from receiving adequate blood flow, as well as creating pressure and other injuries in the area of the rupture or leak. Ischemic stroke occurs when a blood vessel in the brain becomes at least partially blocked, preventing a full supply of blood from passing the blockage to reach other areas of the brain. Stroke may also refer to a transient ischemic attack (TIA), where blood flow to part of the brain is temporarily interrupted, but is restored without intervention. A TIA may be, but is not always, a precursor to a stroke. A person who has experienced a TIA is generally considered at higher risk for stroke than someone who has not experienced a TIA.
Although different people may experience stroke differently, symptoms for hemorrhagic and ischemic stroke, as well as TIA, are generally similar. Symptoms may include slurred, garbled, or nonsense speech and physical asymmetry. For example, a person experiencing a stroke or TIA may have difficulty holding an arm up in an extended position for even a short period of time—the stroke victim may need assistance to lift the arm, or may be unable to hold the arm in a raised position, even if the other arm can easily be raised and held in a raised position. As another example, a person experiencing a stroke or TIA may have a visually perceptible droop or sagging in the face, shoulders, or other body carriage. The droop or sagging may be pronounced, or the asymmetry may be most noticeable with movement, such as when the person smiles or speaks. Typically, weakness and/or drooping are one-sided, occurring predominantly or entirely on the right- or left-side of the body, depending on what part of the brain is affected by the stroke.
Stroke can be treated, however, currently available treatments require prompt action. Medication for ischemic stroke is best delivered within 4-6 hours of the onset of symptoms. Hemorrhagic stroke may require even faster intervention, depending on the severity and location of the rupture or leak. A TIA by definition does not require intervention, however, recognizing the occurrence of a TIA is important to allow for diagnostic and preventative care.